Seaweeds of the British Isles are one of the richest in the world and that’s why through this piece we’ll take a look at Foraging for Seaweeds. Of the 10,700 species of seaweed that have been identified around the world, more than 6%, 635 species, are found on our shorelines.
What is Seaweed?
Seaweeds are the largest and most complex form of marine algae, a diverse group of species which photosynthesise using chlorophyll to produce their own food but do not have some of the specialised cells and tissues of terrestrial plants, such as stomata, phloem and xylem.
There are three main types of seaweed, belonging to the three main groups of algae – green (Chlorophyceae), red (Rhodophyceae) and brown (Phaeophydeae). The green and red algaes are related to the so-called higher plants (mosses, ferns, gymnosperms and flowering plants) whereas the brown algae are related to diatoms, which are phytoplanktons.
All three colours of seaweed contain chlorophyll, the main photosynthetic compound which gives plants their green colour. The green seaweeds get their colour from chlorophyll and also contain beta-carotene as a pigment to supplement the activity of chlorophyll. Red seaweeds also have the red pigments, phycocyanin and phycoerythrin; the brown seaweeds have the brown pigment, fucoxanthin. These different pigments enable the seaweed to use different wavelengths of light to photosynthesise in different depths of sea water. The colour of a particular seaweed indicates, in reverse, which wavelength of light it is able to use for photosynthesis; every one except the colour it is.
You probably already eat seaweed!
Whole seaweeds are included in a range of foods that we buy today including meat and bakery products, like sausages, frozen meats, beef patties, restructured poultry steaks, wholemeal bread, cheeses, pizza bases, pasta and thickening agents in milkshakes, to name a few. If you’re not interested or (like me) not able to read the very small print on the contents labels of processed food, you’ve probably been eating seaweed for ages without knowing it. Eating seaweed directly from the sea is a much better way to enjoy its delicious, nutrient packed, umami flavour.
Why eat seaweed?
With such a rich diversity of seaweed and easy access to the 35,000Km of intertidal seashore from anywhere in the UK, it is surprising that wild seaweed in our diet is restricted mostly to the Celtic ‘fringes’ – mainly Northern Ireland, Wales and North Devon. Seaweeds are extremely good for you. They are the most highly mineralised vegetables on earth, accumulating and concentrating minerals directly from the sea; they contain high levels of vitamins, particularly A and C and have an excellent protein and amino acid profile. Their high iodine content makes them beneficial to the thyroid gland. They are high in soluble fibre which is good for the digestion and they also have the ability to satiate – that is they fill you up and so act as an excellent diet food.
So, where do we find them and which ones can we eat?
Seaweeds grow wherever there is a hard substrate to which they can attach. Even soft muddy shores have seaweeds as there are always shells or the occasional piece of gravel on which to attach. It is important that you only forage seaweed that is still attached to the substrate by its holdfast. If it is floating freely it may have come from further out at sea where poisonous species may be found or where waters are more polluted.
The great thing about seaweed is that all the ones we find growing in the intertidal zone, are not poisonous. The intertidal zone is the area regularly covered and uncovered by the tide. The upper tidal zone is the more landward part of the shore, which is immersed only 20% of the time; the lower tidal zone is the seaward part of the shore, which is immersed 80% of the time. This means we can reach them on foot, without swimming or going out on a boat, though some are below the water even at low tide so you may get your feet wet. Not poisonous doesn’t necessarily mean they are edible – some have a disgusting flavour, others are too slimy or too tough to eat.
Seaweeds can completely cover sheltered shores. In exposed shores the number of seaweeds to be found on open rocks decreases; they are more likely to be found on shaded, north facing rocks or in crevices and runnels.
Below are details of some of the best edible species, organised according to which part of the intertidal zone they are usually found.
Foraging for Seaweeds in the Upper Tidal area
Gutweed, Ulva intestinalis– Green seaweed
Found on all coasts of the British Isles, it grows on rocks or shells or is sometimes detached and found floating at all levels of the intertidal zone and also in brackish dykes; sometimes in freshwater, tidal rivers.
It has thin, green, twisting and turning tubes, 10 – 30cm long and 18mm wide, which, when inflated with oxygen give rise to the latin name intestinalis. It is an annual species found between April and August.
Culinary Uses
Deep-fried crispy seaweed – sweeten it with a little icing sugar and use as a side dish or garnish.
The tangled nature of this seaweed makes it particularly good at trapping sand and small sea creatures so wash several times as described further below.
Benefits
As an Ulva species it has similar nutritional properties to Sea Lettuce, described further below.
Channelled/Channel Wrack, Pelvetia canaliculta – Brown seaweed
Found around most coastlines except East Norfolk, Suffolk and the Thames Estuary, Chanel Wrack likes to be firmly within the splash zone and can blanket large areas of rock.
It has evenly forked, dichotomous, inrolled fronds 5 -15cm long and less than 5mm wide. The inrolled fronds form a channel on one side and a smooth ridge on the other. When dry, the fronds darken from olive green to black. Available all year round but best between May and August. Around August to September the seaweed’s gametes are released from the frond tips into the water for external fertilsation.
Culinary Uses
Cut away only the softer tips; nearer to the holdfast they get wiry and tough. The tips make good additions to salads, stir fries, sandwiches, quiches, pies and soups. It has a strong flavour that can be improved by drying in the sun. You can toast it under a grill for a delicious snack, or dehydrate the seaweed before grinding it into a powder and use it as a thickening, flavouring agent for broths and stews, imparting a savoury umami flavour.
Benefits
Has a high fat content. Very high in Omega 3. Also a high selenium content which could have anti-cancer properties.
Foraging for Seaweeds in the Middle Tidal area
Sea Lettuce/Green Laver/ Oyster-green, Ulva lactuca – Green seaweed
Found on all coasts of the British Isles. Very abundant throughout the inter-tidal areas of rocky shores, on salt marshes and estuaries.
The fronds are thin, light to deep green with wavy margins that vary in size and can reach 1m long and 30cm wide. They are attached to the rocks by a round holdfast.
Culinary Uses
This is a great addition to salads. It is very common and grows throughout the year, so is a a great one to include in your diet on a regular basis.
A very tender seaweed which can be chopped and used as the main ingredient or addition to pasta dishes, risottos and salads. They can be deep fried to make beautiful translucent crisps. You could dry and powder it and experiment with using it as a thickener for soups or even create ice creams.
Benefits
Nutritionally rich in iron, vitamins A, B and C and protein as well as other trace elements. Low in fat and a great source of dietary fibre. The young fronds are said to be tastier in spring but higher in vitamin C if picked in summer. Protein levels peak in August but drop off in April.
It is among the edible marine algae that are rich in phenols and investigated for a potential treatment for diabetes, cancer and diseases caused by free radicals in the body. It may also stimulate the immune system.
Egg Wrack/Knotted Wrack, Ascophyllum nodosum – Brown seaweed
Found on all sheltered shores of the British Isles, where it is common and abundant on stable rocks and boulders.
Tough, long, leathery, compressed fronds growing 30 to 15cm long and up to 1cm wide and brancing in an irregular dichotomous manner. No midrib. Attached by a disc-shaped holdfast. Air bladders are produced at intervals along the main axis and branches. Branches are often parasitised by Wrack Siphon Weed, Vertebrata lanosa.
Culinary Uses
Can be harvested all year round but its growth is slowest in winter. It grows rapidly in April and May but can decline during long periods of sunshine.
It is used in Iceland and Greenland to make herbal tea but otherwise, despite its high nutritional value, it is not normally used as an ingredient. It is sometimes found in health food tablets and provides an alginic acid for gelatine and emulsifying agents. Alginates are also used in pre-prepared pies, instant mixes and sauces; it is also found in wholemeal bread, sausages, frozen meats, pizza bases and cheese.
Bread enriched with an extract of Egg Wrack has been found to reduce energy intake in healthy, overweight males, with no effect on nutrient intake or hunger levels. It can therefore be used for reducing energy intake in diets and for controlling blood sugar and cholesterol levels.
Benefits
Egg Wrack is a very nutritious seaweed. In every 100g it contains
- 150mg of iodine
- 4,200mg of calcium
- 700mg of magnesium
- 100mg of phosphorus
- 50mg of iron an
- 1mg of zinc
- 1g fat
- 10g protein
- 6g fibre
- Vitamins B and C
- It is a valuable source of antioxidants
Medicinal uses
Research has shown that Egg Wrack has considerable antibiotic activity, being effective against bacteria such as Staphylococcus aureus and Escherichia coli.
Bladder Wrack, Fucus vesiculosus – brown seaweed
Found along the entire coastline of the British Isles it grows between the high and low tide mars, usually around the mid point and higher up than toothed wrack.
The fronds are forked with a pronounced midrib, smooth edges and round air bladders, usually in pairs.
The nutritional value of Bladder Wrack varies from season to season. In summer it is particularly high in vitamin A and in autumn has good levels of vitamin C. July is the best time to dry this seaweed to take advantage of its high iodine content.
It also has high levels of protein, phosphorus, bromine and magnesium and is a source of sugars, starches, fats and zinc. Like most brown seaweeds it contains fucoidan which has high antioxidant activity.
Very little of the nutrient content is lost when the seaweed is dried.
Culinary Uses:
Best cooked for a long time, for example with beans which also need to be boiled for long periods. This reduces the rubbery texture to a softer, vegetable-like texture and some of the frond will disintegrate and act as a thickening agent as well as adding flavour.
Fronds can also be on a radiator or in the sun then toast for 20 minutes in a hot oven When dry crush or blend the fronds and use them as a condiment, add them to bread or store them in an airtight container for later use.
Medicinal Uses:
Laboratory studies show that Bladder Wrack may be antibacterial, antiviral, anticoagulant, antilipidaemic (lowers blood cholesterol) and hypoglycaemic (lowers blood sugar). Present day herbalism considers Bladder Wrack to have anti-hypothyroid and anti-rheumatic properties and its nutritional value makes it a useful herb in convalescence.
Serrated Wrack/Toothed Wrack, Fucus Serratus– brown seaweed
This is a brown seaweed found along the entire coastline of the British Isles. It grows on rocks from the lower tidemark to about halfway up to the upper tidemark.
It has many forked fronds from 60 to 180cm long and about 2cm wide. The edges of the fronds are serrated and they have a distinct midrib and pointed, jelly-filled sacks at the tips of some of the branches. The similar Fucus species are also edible but this is the most common.
Culinary Uses
As for Bladder Wrack but the high iodine levels can impart a bitter taste.
Benefits
In Ireland it is used for body care products and seaweed baths. It has a high vitamin E content which is an antioxidant and the free radical scavenging activity has been found to be high compared to other seaweeds. Other bio-activities have been reported including anti-tumour, antivenom and anticoagulant.
Wireweed, Sargasum muticum – Brown seaweed
This is not a native species but was introduced to Britain in the 1970s. It has spread along the south and south west coasts of England and has been found as far north as the Outer Hebrides. Also widely established in Ireland.
Found in shallow sub-tidal and rock pools growing on hard substrata in shallow waters and can also tolerate estuarine conditions.
It is a large, bushy brown seaweed which can grow of 2m long. It has regularly alternating, long, stringy branches with small, spherical bladders on short stalks. The bladders are oval with an irregular outline.
Culinary Uses
Hawaiians have five different species of Sargassum spp and the plant is often included in traditional recipes such as raw seaweed and octopus. A panna cotta has been made pairing coconut milk and Wireweed. On Jeju Island in South Korea, Wireweed is known as Mojaban, a favourite food used for a traditional seafood broth called Mom-guk soup.
Benefits
It has the same potential use of many seaweeds as a valuable source of nutrients and an anti-cancer potential due to high antioxidant component – it is best used fresh as this can be reduced by drying. It is rich in various minerals, vitamins and dietary fibres.
Foraging for Seaweeds in the Lower Tidal area
Nori/Laver, Porphyra spp– Red seaweeds
There are three main types of laver that are used as food in the British Isles.
Porphyra Linearis is found along most coasts of the British Isles, mostly on the upper shore, particularly on rocks near sand; the narrow blades of the red or brown fronds fan out over the sand at low tide; mostly October to April.
Purple Laver, Porphyra purpurea
This is found in more sheltered areas, sometimes extending into estuaries. The fronds are shaped like a large beech leaf, dark purplish yellowish, thin and slippery. Found all year round but more abundant in summer.
Porphyra umbilicalis
Found on rocky beaches on most coasts of the British Isles. It grows just below Porphyra linearis on rocky shores and also attached to stones in sandy areas. It is a green-purplish brown, very thin, sheet-like frond, often attached by a point within the frond. Found all year but mostly in summer.
Culinary Uses
Traditionally used to make laver bread by boiling for several hours. Once boiled it is fried in butter with oats or oatmeal (and cream if desired) and served with bacon or simply spread on toast. Alternatively, fresh fronds can be dry fried and either eaten straight away or stored in an airtight container. In Wales in particular, P. umbelicalis is eaten in salads, biscuits and as an accompaniment to roasted meat.
The Porphyra seaweeds are probably best known as norito which is a popular wrapper for sushi and a flavouring for soups and salads
Benefits
Rich in protein, providing a wide range of amino acids. The vitamin A content is on average 67 times higher than eggs and the vitamin C content 1.5 times higher than oranges.
P. umbelicalis is rich in protein, vitamins A, C, E and B1, B2, B6 and B12. It is a good source of Omega 3, polyunsaturated fatty acids and dietary fibre.
Pepper Dulse, Osmundea pinnatifida – Red Seaweed
Found throughout the British Isles except Lincolnshire and parts of East Anglia and the east coast of Ireland.
It is very abundant on moderately wave-exposed rocky shores, forming a broad zone at most shore heights, covering rock surfaces.
The alternately branched fronds are flat and quite tough. Higher up the shore they are smaller and yellowish green whereas lower down the shore they an reach 8cm long and are reddish brown.
Culinary Uses
Has a peppery flavour and can be used in salads or miso soup to add spice. The distinctive aroma and flavour is mostly present in younger specimens collected in winter and spring.
Benefits
A good source of antioxidants, protein, fatty acids, fibre, vitamins and minerals. It contains 19 times more potassium than cheddar cheese, 38 times more magnesium than whole milk and 46 times more calcium than steak.
Medicinal uses
Some potential for treating bacterial and fungal infections.
Carragheen/Irish Moss, Chondrus crispus – Red seaweed
Found throught the British Isles except Lincolnshire, parts of the East Riding of Yorkshire, Suffolk and Norfolk coasts, it grows on rocky shores, usually under water either in rock pools or below the tidemark.
It is purple, red or even green after prolonged exposure to sunlight, has branched fronds, widening to rounded tips which are iridescent under water, emitting a bluish-pink glow. The whole seaweed is slippery to touch.
Culinary Uses
The gelling properties of Irish Moss have made the seaweed so much a part of our daily diets that many of us fail to realise we are eating it in ice creams, salad dressings and many other processed foods. Traditionally used for milk puddings, they have a slightly fishy after-taste, which can be masked by serving with acidic fruit. They can also be used as thickeners for making set savoury dishes.
Irish Moss drink is made in the West Indies by simmering the fronds in water with cinnamon and linseed until the water thickens, adding condensed milk, nutmeg and vanilla essence. Leave it to cool and whisk to prevent setting.
False Irish Moss is also edible. It has fronds that are thickened at the edges producing a groov in the middle and a U-shaped cross-section. It is covered in small nipple-like reproductive bodies that make it rough to touch. It can be used the same as Irish Moss.
Benefits
It is rich in many nutrients. 100g contains:
- 20-30mg iodine
- 20mg iron
- 900mg calcium
- 2,200 mg sodium
- 3,400mg potassium
- 700mg magnesium
- 800mg phosphorus
- 1 – 3g fats
- 6g fibre
- 15g protein
Medicinal uses
Modern research confirms some of its uses in folk medicine. It is anti-viral, expectorant and soothes dry and irritated mucus membranes, making it useful for coughs, colds and chest complaints. However, cooking may destroy these properties.
It can also be used as a demulcent in gastric ulcers, to relieve constipation and diarrhoea and to sooth inflammation in cystitis and other urinary infections. It is beneficial to gut health, promoting the growth of beneficial, probiotic bacteria.
Dulse/Dillisk, Palmaria palmata – Red seaweed
Found on all coasts of the British Isles, it grows on rocks, other plants, especially Forest Kelp, Laminaria hyperborea stipes. Found both on the shore and in the subtidal one to a depth of 20m in sheltered and moderately exposed areas.
The reddish brown, thin, flat, leathery fronds grow from a disc holdfast and are much divided into lobes which grow 30 – 80mm wide and up to 1m long but usually no longer than 40cm.
Culinary Uses
Dried fronds can be eaten like crisps. It can be boiled for a few minutes, chopped finely and added to garlic mashed potatoes.
Benefits
Nutritionally, Dulse has more protein than foods such as chicken or almonds, comparable to foods such as soybeans. It is almost as rich in iron as Bladder Wrack. Its vitamin A content is highest in summer and vitamin C is higher in autumn. A small amount of dulse can provide more than 100% of the daily allowance of vitamin B6 and 66% allowance of B12, iron and fluoride. It also contains vitamin E, iodine, phosphorus, nitrogen, potassium, magnesium, calcium, sulphur, manganese, titanium, yeast as well as sugar and starch.
Medicinal uses
Historically Dulse was used to treat parasitical infections, to relieve constipation and as a cure for scurvy. Today it is also recognised as a potential medicinal plant, particular for its iodine content. It has also been shown to have potential in reducing the risk of intestinal and mammary cancer in animals, reversing hardening of arteries and reducing high blood pressure and preventing the build up of toxins, waste and even radioactive or heavy metals from the body.
Thongweed/Sea Spaghetti, Himanthalia elongata – Brown seaweed
Found on coasts through the British Isles, except southeast England. It grows on rocky shores close to the low tide mark, below Toothed Wrack.
The fronds are shaped like a concave mushroom but the more noticeable and useful part of this seaweed are the straplike reproductive fronds or receptacles. During the main growth period, February to May, they reach 5 – 25cm long, branching in two several times.
Culinary Uses
Not only does this resemble floating pasta, it can be cooked the same way. Treat it like a vegetable, ribbon pasta and use it as a noodle base or accompaniment to traditional pasta dishes. It has a strong seaweed odour and can be harvested from late spring to early autumn.
It can be dried or pickled or fried on a high heat until browned and crispy.
Benefits
Rich in nutritious amino acids. Contains B vitamins and vitamin A. Per 100g it contains
- 28mg vitamin C
- 59mg iron
- 720mg calcium
Its antimicrobial and antioxidant activity also help to prevent food spoilage.
Medicinal uses
It has antibiotic properties and also an analgesic effect (pain killing) on the central nervous system.
Velvet Horn/Dead Men’s Fingers, Codium fragile – Green Seaweed
This is not a native species but is found on the coasts of south and southwest England, Wales, west and south-east Scotland and Orkney It grows below the low tidemark on rocky coasts.
The fronds are dark green, upright and branched dichotomously, the branches are soft and velvety.
Culinary Uses:
It provides a bulky vegetable which is commonly soaked, sugared and eaten as a delicacy. In China, Japan, Korea and the Philippines it is used in sweets, salads and soups. In Korea it is also made into a tea.
Deep-fry in tempura batter or shallow fry briefly or dry and grind to make a condiment.
Benefits
Good levels of vitamins A and E4. Contains a range of proteins and abundant fatty acids as well as carbohydrates, minerals, sugars, starches and trace elements; particularly high in iron.
Medicinal uses
Has been used as an anticoagulant in the pharmaceutical industry. It shows some antibacterial activity and studies have suggested it may inhibit the development of leukaemia and colon cancer.
Foraging for Seaweeds in the Sub-tidal area
Kelp
Having said earlier that seaweeds can reduce appetite, kelps have the opposite effect as they contain glutamic acids from which monosodium glutamate (MSG) is derived. MSG has appetite enhancing properties, making you feel hungry after you have eaten.
Sugar Kelp, Saccharina latissima – Brown seaweed
Found on all coastal areas of the British Isles, it is an annual species which often colonises unstable or scoured habitats in summer.
This kelp grows to 1.5m, typically with an elongated strap-shaped frond, narrowing towards a rounded apex and with an uneven surface. Below the frond is a flexible, often smooth, thin stipe. Individuals are attached via a claw-like holdfast.
Culinary uses
It an be consumed as a fresh or dry food and its natural sugar content makes it ideal for making alcohol.
The stipes are said to taste like peanuts and it is often eaten as a snack such as fried sweet kelp chips. It is eaten as a vegetable in Japan and Korea and also in France, Denmark, Portugal and Spain.
Benefits
High in protein, iodine, bromine, vitamins B and K, calcium, potassium, manganese, nitrogen, sodium, glutamic acid, nickel and iron. Also high in sugar and starch and therefore makes a tasty snack. It is highest in vitamin C in late spring but highest in sugar content in summer.
Medicinal uses
A good source of antioxidants and phenolic compounds which have antimicrobial properties.
Forest Kelp, Laminaria hyperborea – Brown seaweed
Found on most coastlines of the British Isles except for the east and south-east coasts of England where it is uncommon. It grows on rocky substrates usually below the low water mark but can be found in rock pools.
They grow from 0.5 to 3.5m high with sheet-like lamina, oval shaped, cleft into linear segments, expanding abruptly from a long, rough, cylindrical stipe and attached via a claw like holdfast.
Culinary Uses
In Iceland, Forest Kelp is eaten dried and toasted. It is also eaten in the UK, Ireland, Norway and Spain. It is used in the food industry for making emulsifiers and gelling agents.
Benefits
Forty two different fatty acids have been identified in the seaweed and, along with other Laminaria species it is considered to be richer in vitamins and minerals than any other vegetable.
Medicinal Uses
It has bioactive compounds with anticoagulant, antiviral and anticancer properties.
Tangle/Oarweed, Laminaria digitata – brown seaweed
Found on suitably rocky habitats on most coasts of the British Isles on the extreme lower part of the intertidal zone which is only exposed during neap-tides, every two weeks; sometimes in rock pools if there are solid, stable rocks.
It is deep brown with a thick, oval, rubbery stipe, up to 1.5cm wide and 30cm long. The blade is split by wave action into finger-like segments. The whole algae may be several metres long.
Culinary Uses
A popular method of cooking kelps is deep frying in vegetable oil or sauted or marinated to make seaweed chips. When cooked, kelp turns a deep green. It can be used to wrap fish before barbecuing, keeping it moist and adding a delicate seaweed flavour. In Japan Kelp is used to make a gloopy stock called ‘sashi’ which forms the basis for soups such as miso, noodle broths, dipping sauces and simmered dishes.
Benefits
Rich in minerals and vitamins such as potassium, magnesium, iron and iodine. Vitamin C levels are said to be highest in spring while at that time of year it is lowest in starch. Protein levels are said to be highest in February. The fibre content is twice that of brown rice.
Medicinal uses
Antioxidant and antimicrobial properties. Traditionally used in Chinese herbal medicine for treatment of cancer, they have been demonstrated to have antitumour actions. Also said to have a beneficial effect on gut health.
Dabberlocks/Atlantic Wakame, Alaria esculenta – brown seaweed
Found in Scotland and Ireland, Cornwall, Somerset, Northumberland and westerly parts of the Welsh coast, Dabberlocks grows on rocks near low tide but always under water
Its stipe is 10 – 30cm long and 0.5 – 1.25cm wide, round or oval in cross-section. The wavy, ribbon like blades can be yellow, brown or olive green and up to 4m long, but usually smaller, with a solid midrib almost as wide as the stipe for its entire length. On older plants sporophylls grow out of the sides of the stipe below the blade, around 10cm long.
Culinary Uses
This is very similar to Japanese Wakame, Undaria pinnatifida, and can be used in its place in recipes. The sporophylls and midrib were traditionally eaten in Scotland as a sweet, nutty, peanut-like snack called hinnie waar. The fronds are also eaten in Scotland, Ireland, Iceland, Denmark and the Faroe Islands. Drying or smoking improves the flavour. Dabberlocks are lighter and dry quicker than kelps. Once dried they can be used as a seasoning and stored for later use in a stock.
The dried plant can be rehydrated after soaking in cold water for 20 minutes
Benefits
Contains iodine, bromie, sugars and starches and various trace elements. High in vitamins A, K, C and B it is said to contain the highest vitamin C content in spring but it reaches its greatest bulk in summer and greatest length in winter. It is a viable source of energy providing, per 100g
- 40g carbohydrate
- 3.6g fat
- 18g protein (said to be highest in winter)
Seaweeds have a high value both ecologically and economically. They are important primary producers and they constitute a habitat for a wide range of intertidal and subtidal animals. When foraging for seaweed the same laws and ethics apply as for wild plants and mushrooms. However, rather than not uprooting you should not pull a seaweed up by its holdfast; cut above it allowing the individual to regrow. Closer to the holdfast most seaweeds become tough anyway.
All seaweeds have propensity to trap sand and grit in their fronds so, before eating, cooking or drying, rinse them thoroughly six times – discarding the water between each rinse. Most do not have a very long shelf life so eat, cook or dry them as fresh as possible.
When foraging for seaweed always be aware of the tides and set an alarm to alert you when the tide is coming in, to allow you plenty of time to get back to safe ground before high tide.
More detailed identification guides for most of the species above can be found here.
Here’s more on the health implications of consuming seaweeds